1. Field of the Invention
The present invention relates to liquid crystal displays. More particularly, it relates to liquid crystal display panels in which a liquid crystal is located on a thin film transistor array substrate before the panel substrates are bonded together.
2. Background of the Related Art
In general, a liquid crystal display (LCD) panel includes a first transparent substrate, a second transparent substrate, and a liquid crystal injected between the first and second transparent substrates. The first transparent substrate includes a plurality of gate lines that extend in one direction, a plurality of perpendicular data lines, and a matrix of thin film transistors and pixel electrodes in pixel regions that are defined by the gate lines and the data lines. The second transparent substrate includes a black matrix, for shielding light incident between the pixel regions, and color filters.
The first and second transparent substrates are typically bonded together by a sealing material such that a gap is formed between the two substrates. In the prior art, the liquid crystal is usually injected into the gap. To enable injection, the sealing material is printed with an injection hole through which the liquid crystal is injected. The injection hole is then sealed. If the sealing material does not include an injection hole, the liquid crystal is deposited on one substrate within a volume defined by the sealing material, and then the first and second substrates are bonded together.
FIG. 1 is a plan view of a related art first substrate with a sealing material, FIG. 2 illustrates a section of a related art LCD panel comprised of the sealing material and a liquid crystal on the first substrate, and an adjacent second substrate before the bonding of the two substrates together, and FIG. 3 illustrates a section of a related art LCD panel having a liquid crystal interposed between two bonded substrates.
Referring now to FIG. 1, when fabricating a related art LCD panel a seal 2 comprised of a sealing material is printed around an active array region of a first glass substrate 1. The active array region includes a plurality of gate lines (not shown), a plurality of data lines (not shown), and a matrix of thin film transistors and pixel electrodes (also not shown). As the sealing material does not include an injection hole, an appropriate amount of liquid crystal 3 is dropped onto the first glass substrate 1 and inside the seal 2 by a dispenser. Referring now to FIG. 2, a second glass substrate 4 having a black matrix (not shown) and color filters (not shown) is then located over the first glass substrate 1. Then, as shown in FIG. 3, the first and second glass substrates 1 and 4 are bonded together so as to seal the liquid crystal 3 between the first and second glass substrates 1 and 4.
While conceptually easy to do, the related art method of fabricating LCD panels has problems. First, locating the correct amount of liquid crystal inside the seal 2 is difficult. Second, an excessive amount of liquid crystal inside the seal 2 can lead to damage to the seal 2 during bonding, resulting in a defective panel or a panel with poor adhesion between substrates. In particular, when the liquid crystal 3 contacts the top of the seal 2 the bond between first and second glass substrates 1 and 4 can be weakened.
Therefore, a new method of fabricating LCD panels without an injection opening would be beneficial.